Stable, concentrated herbicidal compositions

ABSTRACT

A liquid herbicidal composition is provided, comprising:
         a. 20 to 35 percent by weight, based on the total weight of the composition, of a water-soluble herbicidal ingredient;   b. a C 12 -C 16  alkyl ether sulfate;   c. an organic solvent; and   d. an alkyl polyglucoside.
 
The composition is stable; i.e., it occurs in a substantially continuous, single phase at temperatures as low as −20° C. It also has a viscosity of no more than 2000 cps at temperatures as low as 0° C.

FIELD OF THE INVENTION

The present invention is directed to biologically active crop protectionformulations, in particular, herbicidal compositions.

BACKGROUND OF THE INVENTION

Aqueous herbicidal formulations of glufosinate-ammonium have beenavailable for decades as crop protectants. Popular formulations includesurfactants, which increase the biological activity of the herbicide.High concentration formulations are being sought as well for thenumerous advantages they offer; for example, less packaging is neededthan with low-concentration formulations, corresponding to reductions inthe cost and inconveniences of production, transit, and storage.Preparation of spray liquors is also simplified by the smallerquantities of crop protectant that need to be handled. However, certaindrawbacks have been observed in higher concentration formulations. Forexample, the biological activity of the active ingredient is dependenton the proportion of active ingredient to surfactant, but if the amountof surfactant is too high, the viscosity of the composition may becometoo high for easy handling or spraying. Product instability such asphase separation has also been a drawback of highly concentratedformulations. Phase separation is undesirable because the concentrationof various essential ingredients is no longer uniform throughout thecomposition.

It would be desirable to provide a high-concentration herbicidalcomposition that overcomes the drawbacks of the prior art bydemonstrating enhanced biological activity in a stable formulationwithout compromising viscosity requirements.

SUMMARY OF THE INVENTION

A liquid herbicidal composition is provided, comprising:

-   -   a. 20 to 35 percent by weight, based on the total weight of the        composition, of a water-soluble herbicidal ingredient;    -   b. a C₁₂-C₁₆ alkyl ether sulfate;    -   c. an organic solvent; and    -   d. an alkyl polyglucoside.

The composition is stable, occurring in a substantially continuous,single phase at temperatures as low as −20° C. It also has a viscosityof no more than 2000 cps at temperatures as low as 0° C.

DETAILED DESCRIPTION OF THE INVENTION

Other than in the operating examples, or where otherwise indicated, allnumbers expressing quantities of ingredients, reaction conditions and soforth used in the specification and claims are to be understood as beingmodified in all instances by the term “about.” Accordingly, unlessindicated to the contrary, the numerical parameters set forth in thefollowing specification and attached claims are approximations that mayvary depending upon the desired properties sought to be obtained by thepresent invention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical values, however, inherently contain certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

Also, it should be understood that any numerical range recited herein isintended to include all sub-ranges subsumed therein. For example, arange of 1″ to 10″ is intended to include all sub-ranges between andincluding the recited minimum value of 1 and the recited maximum valueof 10, that is, having a minimum value equal to or greater than 1 and amaximum value of equal to or less than 10.

As used herein, unless otherwise expressly specified, all numbers suchas those expressing values, ranges, amounts or percentages may be readas if prefaced by the word “about”, even if the term does not expresslyappear. Any numerical range recited herein is intended to include allsub-ranges subsumed therein. Plural encompasses singular and vice versa;e.g., the singular forms “a,” “an,” and “the” include plural referentsunless expressly and unequivocally limited to one referent. Also, asused herein, the term “polymer” is meant to refer to prepolymers,oligomers and both homopolymers and copolymers; the prefix “poly” refersto two or more.

With respect to the present invention, the term “stable” as used hereinis intended to refer to physically stable compositions; i.e., liquidcompositions that exist in a substantially continuous, single phase.

In the context of the present invention the term “organic solvents”refers to, for example, nonpolar solvents, polar protic solvents,aprotic polar solvents and mixtures thereof.

The liquid herbicidal composition of the present invention comprises awater-soluble herbicidal ingredient (a). Non-limiting, suitable examplesinclude glufosinate and salts thereof such as glufosinate-ammonium,glyphosate and salts thereof, paraquat, diquat, and the like. Mixturesmay also be used.

Typically the water-soluble herbicidal ingredient may comprise acompound of the formula (I) and/or salts thereof:

wherein Z₁ is a radical of the formula —OM, —NHCH(CH₃)CONHCH(CH₃)CO₂M,or —NHCH(CH₃)CONHCH[CH₂CH(CH₃)₂]CO₂M, where M is H or a salt-formingcation.

The water-soluble herbicidal ingredient may alternatively oradditionally comprise a compound of the formula (II) and/or saltsthereof:

wherein Z₂ is a radical of the formula CN or CO₂R₁, in which R₁ is asalt-forming cation or is H, alkyl, alkenyl, alkoxyalkyl or C₆-C₁₀ aryl,which is unsubstituted or substituted, and is often unsubstituted orsubstituted by one or more radicals such as alkyl, alkoxy, halogen, CF₃,NO₂ and CN; and wherein R₂ and R₃ are each independently H, alkyl orC₆-C₁₀ aryl, which is unsubstituted or substituted and is oftenunsubstituted or substituted by one or more radicals such as alkyl,alkoxy, halogen, CF₃, NO₂ and CN, or biphenylyl or a salt-formingcation. Typically, the carbon-containing radicals defined as R₂ or R₃have up to 10 carbon atoms, usually up to 6 carbon atoms.

Note that the compounds of formula (I) contain an asymmetric carbonatom. The L enantiomer has been observed to be the biologically activeisomer. The formula (I) therefore is intended to encompass allstereoisomers and mixtures thereof, particularly the racemate, and thebiologically active enantiomer in each case. Examples of activeingredients of the formula (I) include glufosinate and/or its ammoniumsalt such as in a racemic mixture; i.e.,2-amino-4[hydroxy(methyl)phosphinoyl]butanoic acid and its ammoniumsalt, the L enantiomer of glufosinate and its ammonium salt or othersalts such as potassium, sodium, diethylamine, triethylamine,bilanafos/bialaphos; e.g.,L-2-amino-4-[hydroxy(methyl)phosphinoyl]butanoyl-L-alaninyl-L-alanineand its sodium salt.

The water-soluble herbicidal ingredient may be present in thecomposition of the present invention in an amount of 20 to 35 percent byweight, often 20 to 30 percent by weight, and more often 22 to 28percent by weight, based on the total weight of the composition. Notethat because the water-soluble herbicidal ingredient is typicallyprovided in a 50 percent by weight aqueous solution, an equal amount ofwater is usually provided with the water-soluble herbicidal ingredient.The numbers in the ranges above reflect the amount of herbicide only,not the total solution amount. Additional water may be added asnecessary.

The composition of the present invention further comprises an alkylether sulfate (b). Alkyl ether sulfates are generally defined as saltsof sulfated adducts of ethylene oxide with fatty alcohols containingfrom 8 to 16 carbon atoms. The alkyl ether sulfates used in thecomposition of the present invention are commercially available and maycontain a linear aliphatic group having from 8 to 16 carbon atoms,usually from 12 to 16 carbon atoms. The degree of ethoxylation may befrom 1 to 10 moles of ethylene oxide, usually 2 to 4 moles of ethyleneoxide. Examples include sodium lauryl ether sulfate, ammonium laurylether sulfate, and other salts of lauryl ether sulfate. The alkyl ethersulfate most often used in composition of the present invention issodium lauryl ether sulfate (SLES); typically supplied as an approximate70% active solution, derived either from vegetable or petroleum sources.

The alkyl ether sulfate may be present in the composition of the presentinvention in an amount of 3 to 35 percent by weight, often 10 to 30percent by weight, more often 20 to 30 percent by weight, based on thetotal weight of the composition.

The composition of the present invention further comprises an organicsolvent (c). Suitable solvents may include cyclic alcohols such astetrahydrofurfuryl alcohol; aliphatic alcohols, such as alkanols having1 to 12 carbon atoms, usually 1 to 6 carbon atoms, such as methanol,ethanol, propanol, isopropanol and butanol, for example, or polyhydricalcohols such as ethylene glycol, propylene glycol, dipropylene glycol,and glycerol; ethers such as diethyl ether, tetrahydrofuran (THF), anddioxane; alkylene glycol monoalkyl and dialkyl ethers, such as propyleneglycol monomethyl ether, propylene glycol monoethyl ether, ethyleneglycol monomethyl and monoethyl ether, diglyme, and tetraglyme, forexample; amides such as dimethylformamide (DMF), dimethylacetamide,dimethylcaprylamide, dimethylcapramide (HALLCOMID®), andN-alkylpyrrolidones; ketones such as acetone, cyclohexanone,acetophenone, butrylolactone; esters based on glyceryl and carboxylicacids, such as glyceryl mono-, di- and triacetate, phthalic esters,ethyl lactate, 2-ethylhexyl lactate; lactams; carbonic diesters;nitriles such as acetonitrile, propionitrile, butyronitrile, andbenzonitrile; sulfoxides and sulfones such as dimethyl sulfoxide (DMSO)and sulfolane; carbonates such as propylene or butylene carbonate.Combinations of different solvents, additionally containing alcoholssuch as methanol, ethanol, n- and isopropanol, and n-, iso-, tert- and2-butanol, are also suitable.

Solvents that are most often used in the composition of the presentinvention include individual solvents or solvent mixtures that aresubstantially miscible with water, in order to maintain the phasestability of the composition.

The organic solvent may be present in the composition of the presentinvention in an amount of 1 to 20 percent by weight, often 3 to 10percent by weight, based on the total weight of the composition.

The alkyl polyglucosides (d) which may be used in the present inventionare those corresponding to formula (III):R₄O(R₅O)_(b)(Z₃)_(a)  (III)wherein R₄ is a monovalent organic radical having from 6 to 30 carbonatoms; R₅ is a divalent alkylene radical having from 2 to 4 carbonatoms; Z₃ is a glucose residue having 5 or 6 carbon atoms; b is a numberranging from 0 to 12; and a is a number ranging from 1 to 6.Non-limiting examples of commercially available alkyl polyglucosidesinclude, for example, APG®, AGNIQUE®, or AGRIMUL® surfactants fromCognis Corporation, Cincinnati, Ohio; Atlox surfactants from Uniqema,New Castle, DE 19720; or AG surfactants from AKZO NOBEL SurfaceChemistry, LLC, such as:1. AGNIQUE PG 8105 Surfactant—an alkyl polyglucoside in which the alkylgroup contains 8 to 10 carbon atoms and having an average degree ofpolymerization of 1.5.2. AGNIQUE PG 8166 Surfactant—an alkyl polyglucoside in which the alkylgroup contains 8 to 16 carbon atoms and having an average degree ofpolymerization of 1.6.3. AGNIQUE PG 266 Surfactant—an alkyl polyglucoside in which the alkylgroup contains 12 to 16 carbon atoms and having an average degree ofpolymerization of 1.6.4. AGNIQUE PG 9116 Surfactant—an alkyl polyglucoside in which the alkylgroup contains 9 to 11 carbon atoms and having an average degree ofpolymerization of 1.6.5. AGNIQUE PG 264-U Surfactant—an alkyl polyglucoside in which the alkylgroup contains 12 to 16 carbon atoms and having an average degree ofpolymerization of 1.4.6. AGNIQUE PG 8107 Surfactant—a C₈₋₁₆ alkyl polyglucoside in which thealkyl group contains 8 to 10 carbon atoms and having an average degreeof polymerization of 1.7.7. AGNIQUE PG 266 Surfactant—a C₁₂₋₁₆ alkyl polyglucoside in which thealkyl group contains 12 to 16 carbon atoms and having an average degreeof polymerization of 1.6.8. AL 2575/AL 535 Surfactant—a C₈₋₁₁ alkyl polyglucoside in which thealkyl group contains 8 to 11 carbon atoms and having a HLB 12-13.9. Akzo Nobel AG 6202, AG 6206, or AG 6210 surfactants which are 2ethylhexyl branched C8; linear hexyl C6; and linear C8-C10 alkylpolyglucosides respectively.

The alkyl polyglucoside may typically comprise a C₆-C₁₆ alkylpolyglucoside. The alkyl polyglucosides most often used in thecomposition of the present invention are those of formula III wherein R₄is a monovalent organic radical having from 8 to 10 carbon atoms; b iszero; and a is a number having a value from 1 to 3, typically 1.5 to1.7, often 1.6.

The alkyl polyglucoside may be present in the composition of the presentinvention in an amount of 1 to 15 percent by weight, often 6 to 12percent by weight, based on the total weight of the composition.

While the liquid herbicidal compositions of the present invention may bewaterborne or solventborne, they are more often waterborne (aqueous).

In the composition of the present invention, the weight ratio of thewater-soluble herbicidal ingredient (a) to the alkyl ether sulfate (b)may range from 1:0.2 to 1:5.0, often 1:0.8 to 1:1.2. In addition, theweight ratio of the water-soluble herbicidal ingredient (a) to theorganic solvent (c) may range from 1:0.02 to 1:1, often 1:0.1 to 1:0.3.While not intending to be bound by theory, it has been observed thatkeeping the ratios of the various ingredients within these rangesenhances the biological activity of the herbicidal ingredient comparedto when it is used alone, without compromising the stability of thecomposition. Moreover, the viscosity of the composition may bemaintained within a desired range.

Unlike concentrated herbicidal compositions of the prior art, thecomposition of the present invention is both stable and sprayable over awide temperature range. The viscosity of the composition is typically nomore than 2000 cps, often no more than 1500 cps, more often no more than1000 cps, at temperatures as low as 0° C. Viscosity may be measuredusing any technique known to those skilled in the art, for example,using a Brookfield Synchro-lectric Model LVT Viscometer. An apparentviscosity is measured by first stirring the sample with a glass rod for10 seconds, placing the sample on the instrument, turning the instrumenton, and measuring the value after 3 revolutions of the measuring dial.Typically the measurement is made using a #3 spindle rotating at 30RPMs; however depending upon the viscosity of the sample, differentspindles and differing rotational speeds can be utilized, as known bythose skilled in the art.

The composition of the present invention may optionally includeauxiliary agents commonly used in herbicide formulations and known tothose skilled in the art. Examples include wetting agents, dispersants,emulsifiers, penetrants, preservatives, antifreezes and evaporationinhibitors such as glycerol and ethylene or propylene glycol, sorbitol,sodium lactate, fillers, carriers, colorants including pigments and/ordyes, pH modifiers (buffers, acids, and bases), salts such as calcium,magnesium, ammonium, potassium, sodium, and/or iron chlorides,fertilizers such as ammonium sulfate and ammonium nitrate, urea, anddefoamers.

Suitable defoamers include all customary defoamers includingsilicone-based and those based upon perfluoroalkyl phosphinic andphosphonic acids, in particular silicone-based defoamers, such assilicone oils, for example.

Defoamers most commonly used are those from the group of linearpolydimethylsiloxanes having an average dynamic viscosity, measured at25° C., in the range from 1000 to 8000 mPas (mPas=millipascal-second),usually 1200 to 6000 mPas, and containing silica. Silica includespolysilicic acids, meta-silicic acid, ortho-silicic acid, silica gel,silicic acid gels, kieselguhr, precipitated SiO₂, and the like.

Defoamers from the group of linear polydimethylsiloxanes contain astheir chemical backbone a compound of the formulaHO—[Si(CH₃)₂—O—]_(n)—H, in which the end groups are modified, byetherification for example, or are attached to the groups —Si(CH₃)₃.Non-limiting examples of defoamers of this kind are RHODORSIL® Antifoam416 (Rhodia) and RHODORSIL® Antifoam 481 (Rhodia). Other suitabledefoamers are RHODORSIL® 1824, ANTIMUSSOL 4459-2 (Clariant), Defoamer V4459 (Clariant), SE Visk and AS EM SE 39 (Wacker). The silicone oils canalso be used in the form of emulsions.

The present invention will further be described by reference to thefollowing examples. The examples are merely illustrative of theinvention and are not intended to be limiting. Unless otherwiseindicated, all parts are by weight.

EXAMPLES

The following examples (1 to 9) illustrate the preparation of variousherbicidal compositions, demonstrating combinations of co-solvents andalkyl polyglucosides and their combined effects on stability. Examples1, 3, and 7 are illustrative of the invention while Examples 2, 4-6, 8,and 9 are comparative. The ingredients were mixed together in a suitablevessel at room temperature in the order listed and were observed forphase separation at room temperature. Note that ingredients may be mixedin other sequences, For example, the herbicide may be added to thesolvent package, provided the solution does not phase separate.

1 2 3 4 5 6 7 8 9 Glufosinate 50% 44.00 44.00 44.00 44.00 44.00 44.0044.00 44.00 44.00 SLES (sodium lauryl 38.00 38.00 38.00 38.00 38.0038.00 38.00 38.00 38.00 ether sulfate) 70% BREAK THRU S200¹ 1.00 1.001.00 1.00 1.00 1.00 1.00 1.00 1.00 THFA 7.00 7.00 7.00(tetrahydrofurfuryl alcohol) Propylene glycol 7.00 7.00 7.00 monomethylether Dipropylene Glycol 7.00 7.00 7.00 Iso-propanol 3.00 3.00 3.00Iso-Butanol 3.00 3.00 3.00 1-Butanol 3.00 3.00 3.00 AKZO 6206 Linear5.00 5.00 5.00 Hexyl polyglycoside² AKZO 6202 2- 5.00 5.00 5.00ethylhexyl polyglycoside³ AL 2575 C8-10 5.00 5.00 5.00 Alkylpolyglycoside⁴ Sodium Xylene 1.75 1.75 1.75 Sulfonate 40% aqueous SodiumToluene 1.75 1.75 1.75 Sulfonate 40% aqueous Ammonium Sulfate, 0.70 0.700.70 Granular FLUOWET PL80B⁵ 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.250.25 Deionized Water 1.05 1.05 1.05 RESULTS: Separation of sample No YesNo Yes Yes Yes No Yes Yes ¹Ethoxylated trisiloxane available fromDegussa Corporation ²Linear hexyl polyglucoside available from AkzoNobel AG ³2 ethylhexyl branched polyglucoside available from Akzo Nobel⁴C₈₋₁₁ alkyl polyglucoside in which the alkyl group contains 8 to 11carbon atoms and has a HLB 12-13 ⁵Defoamer available from Clariant

Examples 10 to 12

Examples 10 to 12 illustrate the effects of dipropylene glycol withvarious co-solvents. Example 10 is a composition of the presentinvention while Examples 11 and 12 are comparative.

10 11 12 INGREDIENT: % grams % grams % grams Glufosinate 50% 44.00 88.0044.00 88.00 44.00 88.00 SLES 70% 38.00 76.00 38.00 76.00 38.00 76.00BREAK THRU S200 1.00 2.00 1.00 2.00 1.00 2.00 Dipropylene Glycol 7.0014.00 7.00 14.00 7.00 14.00 Iso-propanol 3.00 6.00 Iso-butanol 3.00 6.001-butanol 3.00 6.00 AKZO 6206 Linear 5.00 10.00 Hexyl polyglycoside AKZO6202 2- 5.00 10.00 ethylhexl polyglycoside AL 2575 C8-C10 5.00 10.00Alkyl polyglycoside Sodium Xylene 1.75 3.50 Sulfonate 40% Sodium Toluene1.75 3.50 Sulfonate 40% PLANTAPON 1.75 3.50 CMGS¹ FLUOWET PL80B 0.250.50 0.25 0.50 0.25 0.50 TOTAL: 100.00 200.00 100.00 200.00 100.00200.00 RESULTS: Viscosity, cps- Initial 140 NT NT Room TemperatureAppearance - Initial no separation separation separation Room Temp. NT -Not Tested due to separation of samples in study. ¹Surfactant availablefrom Cognis-Care Chemicals

Example 13 Comparative

Each composition in the following example contained, in parts by weight:

Glufosinate 50% Concentrate 49 BREAK THRU 9903 Antifoam¹ 0.8 BREAK THRUS200 Silicone Surfactant² 0.6 Potassium Hydroxide 50% Solution 0.12^(1, 2)Available from Degussa Corporation

SLES Example Solution % AL 2575 % THFA % % Separation 13a 37.24 5.5 6.741.8 13b 35.62 4.5 9.36 17.8 13c 34 5.5 9.98 10.9 13d 34 4.5 10.98 12.9613e 34 3.5 11.98 23.6 13f 37.24 3.5 8.74 12.7 13g 36.43 5 8.05 10.7 13h35.08 3.5 10.9 21.8 13i 36.16 3.5 9.82 16.1 13j 35.08 5.5 8.9 7.4

While each of the mixtures in the above set exhibited some degree ofseparation, the amount of separation was less as the level of THFAsolvent decreased and the level of APG surfactant increased. Percentseparation is a measurement of the height of a separated phase comparedto the total height of a sample.

Example 14

The following example illustrates the preparation of an herbicidalcomposition in accordance with the present invention. The ingredientswere mixed together in the order listed:

Percent by weight INGREDIENT: Glufosinate 50% 48.600 AGNIQUE SLES 270¹34.544 AGNIQUE PG 8105² 9.850 THFA 5.500 BREAK THRU S200 0.600 BREAKTHRU AF 9903 0.800 Potassium Hydroxide 50% Solution 0.100 D&C Red 170.006 TOTAL 100.000 RESULTS Gms Glufosinate/liter 280.00 LbsGlufosinate/Gal 2.335 Viscosity cps - R.T. 216 Viscosity cps - 40°F./4.4° C. 640 Viscosity cps - 32° F./0° C. 788 Viscosity cps - 12°F./−10° C. 5400 ^(1, 2) Available from AKZO NOBEL Surface Chemistry, LLC

Whereas particular embodiments of this invention have been describedabove for purposes of illustration, it will be evident to those skilledin the art that numerous variations of the details of the presentinvention may be made without departing from the invention as defined inthe appended claims.

What is claimed is:
 1. A liquid herbicidal composition comprising: a. 20to 35 percent by weight of glufosinate or a salt thereof, based on thetotal weight of the composition; b. 10 to 30 percent by weight of sodiumlauryl ether sulfate, based on the total weight of the composition; c. 1to 20 percent by weight of an organic solvent selected from the groupconsisting of propylene glycol monomethyl ether, tetrahydrofurfurylalcohol, dipropylene glycol, and iso-propanol, and mixtures thereof,based on the total weight of the composition; and d. 1 to 15 percent byweight of a C₆-C₁₆ alkyl polyglucoside, based on the total weight of thecomposition.
 2. A liquid herbicidal composition comprising: a. 20 to 35percent by weight of glufosinate or a salt thereof, based on the totalweight of the composition; b. 3 to 35 percent by weight of sodium laurylether sulfate, based on the total weight of the composition; c. 1 to 20percent by weight of an organic solvent comprising propylene glycolmonomethyl ether and dipropylene glycol, and mixtures thereof; and d. 1to 15 percent by weight of a C₆-C₁₆ alkyl polyglucoside, based on thetotal weight of the composition.
 3. The liquid herbicidal composition ofclaim 2 comprising: a. 20 to 35 percent by weight ofglufosinate-ammonium, based on the total weight of the composition; b. 3to 35 percent by weight of sodium lauryl ether sulfate, based on thetotal weight of the composition; c. 1 to 20 percent by weight of anorganic solvent comprising propylene glycol monomethyl ether anddipropylene glycol, and mixtures thereof; and d. 1 to 15 percent byweight of C₈-C₁₀ alkyl polyglucoside, based on the total weight of thecomposition.